Lifting-jack



(No Model.)

J. BARRETT. LIFTING JACK.

No. 455,994. Patent ed July 14, 1891;

UNITED STATES PATENT OFFICE,

JOSIAH BARRETT, OF ALLEGHENY, ASSIGNOR TO THE DUFF MANUFAC- TURINGCOMPANY, OF PITTSBURG, PENNSYLVANIA.

LlFTlNG-JACK.

SPECIFICATION forming part of Letters Patent No. 455,994, dated July 14,1891,

Original application filed February 1 3, l 89 1, Serial No. 3 81,2 '75Divided and this (Nomodeh) application filed April 30, 1891. Serial No-391,066.

I mechanism in which a step-by-step' movement back and forth isobtained-said mechanism being actively operative in one direction tomove or raise a load andpassively operating in the other direction tocontrol the movements of the load, such as lowering a load lifted by thejack. By such terms it is of course to be understood that the inventionincludes any device embodying its principle whether the power is exertedin a vertical, horizontal, or other line. My invention relates moreparticularly to that class of lifting-jacks described in LettersPatentNo. 399,470, granted to me March 12,1889, and its reissue, No.11,051, dated December 31, 1889, in which jack the operating-levercarries a single pawl to engage with a bar hav-' 'ing a toothed face onone side thereof, and a detent is pivoted on the machine-frame to engagewith such toothed bar and hold the same during the backward movementrofthe operating-pawl, while connections are formed between the pawl anddetent, so that the one may be alternately lifted from connections withsuch toothed bar when it is desired to operate the jack in the oppositedirection, such as in lowering the, load.

The object of the present'invention is to simplify the jack described insaid patent; and it consists, generally stated, in combin ing a barhaving a toothed face on one side thereof, a frame having the operatingor hand lever mounted therein, a pawl carried by the hand-lever andhaving a finger or projection thereon, a detent mounted on the p jack-frame, a yielding trippin g-plate mounted on said frame, and atripping-lever carried by the detent, one end of which engages with theyielding tripping-plate and the other with the projection on the pawl,so that in lowering the jack or imparting an equivalent motion theretoas the pawl is raised said lever will press on the finger thereof andforce the pawl into engagement with the toothed forth and claimed.

To enable others skilled in the art to make .ments, as hereinafter moreparticularly set and use my invention, I will describe the same morefully, referring to the accompanying drawings, in which- Figures 1 and 2are side views, partly broken away, illustrating the operation of thejack.

Like letters of reference indicate like parts in each.

The jack has the body or frame a and the toothed bar I), the exactconstruction of the ends of these two parts not being illustrated, as itis not considered of importance, and for the ordinary lifting-jack hasbeen shown in said Letters Patent above referred to. The

toothed bar, where it is the movable element and raises the load placedupon it, is mounted in a rectangular or other shaped passage formed inthe frame a, such passage being open at the back of the frame, so topermit the movement of the foot of the toothed bar. The frame a has thebearin a for the reception of the pintle at the inner end of theOperating or hand lever c, and pivoted to said operating-lever is thepawl (l, which en gages with the toothed bar I), said toothed bar havingthe teeth formed only on one face thereof, and said pawl (Z acting to.lift the bar as the hand-lever is lowered.

course desirable in obtaining the lifting action to have the pawloperate as nearly in a line parallel with the lifting-bar as possible;but in the ordinary vertical jack this is not found practicable unlesssome counter-weight It is of or spring mechanism is provided for forcingthe pawl into engagement with the toothed bar, and it has generally beenconsidered necessary to give such an inclination to the pawl as to causeit to engage with the toothed bar of its own weight, and consequently ithas not been considered practicable to obtain the lifting movement in aline as near parallel with the toothed bar as desirable. A furtheradvantage of such a mounting of the pawl is that the downward stroke ofthe handlever imparts a longeror shorter stroke of the lifting-pawl,according to its position with relation thereto and whether the basethereof is drawn back by the movement of the handlever.

For reasons hereinafter stated, in the jack forming the subject of thisapplication I am enabled to place the pawl more in line with the toothedbar, and therefore to obtain a better stroke thereon, as I provide themeans of obtaining pressure to force it into contact with the toothedbar. Mounted on. the jackframe a is the detent e, which is arrangedoutside of the pawl, being pivoted below the upper end of the pawl andextending above the pawl, so as to engage with the toothed bar above thesame, the purpose of such detent being to sustain the load which islifted by the pawl d, the detent having, however, no lifting motion.

For the purpose of lowering the jack or forming the backward movement ofeither the toothed bar or the frame in which the operative parts aremounted, I provide the mechanism forming the subject of the presentapplication for drawing the detent out of engagement with the toothedbar, while the lifting-pawl is operated by the mechanism described inapplication for patent filed byme February 13, 1891, Serial No. 381,275,of which this application is in part a division.

Mounted upon the machine-frame is the] tripping-plate g, saidtripping-plate being mounted so as to yield and being pressed forward bythe spring h, secured to the jackframe, the tripping-plate shown beingpivoted to the jack-frame at g. The spring h illustrated is coiledaround a stud h on the jackframe, and one arm b thereof engages with thefrar'ne, while the other arm engages with a pin or seat 77/3 on thetripping-plate. Said tripping-plate 00 has a shoulder 70, with which afinger or projection Z, rigid with the pawl d,

engages, so as to apply pressure to such pawl and draw it out ofengagement with the' toothed bar as the pawl descends and the fingercomes in contact with the shoulder k on the yielding tripping-plate, thetripping-plate yielding against the pressure of the spring h until theload is taken by the detent 6, when the pressure of the spring will,through said tripping-plate, draw the pawl out of engagement with thetoothed bar.

In order to operate the detent e, I mount thereon a projection extendingout therefrom, and rigid therewith the tripping-lever m, this leverhaving preferably about the shape shown in the drawings, one arm r ofwhich extends over pawld, while the other arm 3 extends down to theyielding tripping-plate and engages with the shoulder 19 thereon. As aresult of such construction, when the pawl d is being raised. so as totake a new hold upon the toothed bar and lower it into another notch,the pin or finger n will force upwardly and backwardly the upper arm 0"of the lever m. As the load is carried by the detent e, however, suohpressure on the lever has no effect on the detent e, the lever m simplyswinging onits pivotal point on the detent, its lower arm 5 pressingback the yielding tripp ng-- plate g and so compressing the spring 7thereof. This is continued as the liftingpawl is raised and until thelifting-pawl itself engages with the toothed bar and relieves the detentof the load. In such case as soon as the detent is released the furtherupward movement of the upper end pawl, acting upon the upper end or armr of the lever 'm, 1 with the pressure of the tripping-plate g upon thelower arm 3 of the lever m, will, through said lever, draw thedetentoutfrom the toothed bar, so that as the pawl is lowered the detentwill be held free from the toothed bar a sufficient distance-to permitthe detent to pass one tooth of the bar, when it will receive and holdthe load until the toothed bar is withdrawnby the finger Z pressing uponthe shoulder of the yielding tripping-plate and is raised so as to passone of the teeth and again engage with the toothed bar. A very simplemechanism is thus provided for the operation of the detent, so astoenable it to work alternately with the pawl to lower the load. At thesame time, by means of the lever m, which always presses upon the pin orfinger n of the pawl d, a sufficient pressure to throw such pawl intoengagement with the toothed bar in operating the mechanism in onedirection or the other is obtained, the inclined lower face of the arm0" of the lever 4% always bearing uponthe pin n, and so exerting apressure to force the pawl inwardly, this pressure being increased,however, in the operation of lowering the jack, as the lever on willthen bear upon the shoulder 19 of the yielding trippingplate while thepin or finger is traveling along the under surface of the arm r of saidlever and acting to compress the spring or force back thetripping-plate, and as soon as the finger Z is freed from the shoulderis of the tripping-plate said lever no will force the pawl (1 forwardinto engagement with the toothed bar. As the result of this constructionI am enabled to pivot the pawl 01 more on a line with the toothed barand to obtain a greater lifting action thereof by the exertion of thethe pin or finger n on the' together quires practically few parts. Itcan be changed so as to operate in one direction or the other simplyby'holding backthe yielding trippingplate, which may be accomplished inany desired way, that shown in the drawings being by'means of a cam 15pressing against an arm of the tripping-plate.

As above referred to, in the term jack I include any mechanism in whicheither main element-that is, the toothed bar or the frame carrying theoperative mechanism -has a step-by-step movement which is activelyoperative in one direction to move or raise a load and is'passivelyoperative in the opposite direction either to lower the load or tocontrol its movement whether the same acts vertically,horizontally,curvilinear, or-inother direction.

What I claim as my invention, and desire to secure by Letters Patent, is

1. In a jack, the combination of a bar having teeth on one face thereof,a frame having the operating-lever pivoted therein, a pawl pivoted tosaid lever and carrying a projection or finger rigid therewith, a detentmounted on the frame and having a tripping-lever pivoted thereto andhaving one arm engaging with the finger of the pawl, and a yieldingtripping plate engaging with the other arm of the tripping-lever,substantially as and for the purposes set forth.

2. In a jack, thecombination of a bar having teeth on one face thereof,a frame having the operating-lever mounted therein, a pawl cl, pivotedto said lever and carrying the tingers Z n, rigid therewith, the detente, mounted V in the jack-fra1ne,the tripping-leverm, mounted on saiddetent and having the arm 0', engagin g with said finger n on the pawl,and having the arm 8, and the yielding trip in g-plate having theshoulders k and p, en aging, respectively, with said finger Z and saidarm 8 of the tripping-lever, substantially as and for the purposes setforth.

3. In a jack, the combination of a bar having teeth on one face thereof,a frame having an operating-lever mounted therein, a pawl pivoted tosaid lever and carrying a projection or finger, a yieldingtripping-plate mounted

